The main goal of this project is to develop efficient stereospecific syntheses of a class of nor-diterpenoid dilactones isolated from several different species of the genus Podocarpus (Podocarpaceae). Many of these compounds show a wide range of biological action, including activity against leukemia in mice and cytotoxicity in vitro towards cells derived from both human carcinoma of the nasopharynx (KB) and P-388 murine leukemia. Recent studies have also revealed a strong cytotoxicity against Yoshida sarcoma for several of these lactones. In addition, many of these substances show novel plant growth inhibitory properties. Despite these important biological activities, none of the Podocarpus dilactones have been synthesized. The research proposed herein is designed to provide preparatively useful routes to these cl sely related compounds. A desirable synthesis will be adaptable for the production of all of the primary structures starting from a single precursor and will also possess sufficient synthetic flexibility to be amenable to the synthesis of analogs. Methods for interconverting the different members of this class of substances will also be investigated. Finally, our synthetic strategy will almost certainly require that we develop new synthetic methodologies: These new procedures, besides benefiting this project, should also find considerable application in other synthetic projects, thus assisting numerous other investigators in biology and chemistry.